Pneumatic suspension system

ABSTRACT

The invention relates to a pneumatic suspension system comprised of at least the following pneumatic suspension components, namely of: (a) a pneumatic suspension bellows made of an elastomeric material which encloses an air chamber whose volume varies, and provided, for the most part, with an embedded strengthening support; (b) a pressure reservoir comprising a first fastening area with an outer diameter on which one end of the pneumatic suspension bellows is fastened by means of a clamping ring, whereby the outer diameter includes the clamping ring, and; (c) a pneumatic suspension piston comprising a second fastening area with an outer diameter on which the other end of the pneumatic suspension bellows is also fastened by means of a clamping ring, whereby the outer diameter also includes the clamping ring, as well as comprising a roll-off piston with an outer diameter on whose outer wall the pneumatic suspension bellows can roll off while forming a first rolling fold. The inventive pneumatic suspension system is characterized in that the pressure reservoir, while increasing the outer diameter thereof, is provided with a contoured roll-off surface outside of the first fastening area. The roll-off surface has a beginning and an end and is provided for a second rolling fold which constantly rests against the roll-off surface and which can roll off in only a limited manner compared to the first rolling fold.

[0001] The invention relates to a pneumatic suspension system comprisedof at least the following pneumatic system components, notably of

[0002] a pneumatic suspension bellows made of an elastomeric material,which encloses an air chamber with a variable volume and is providedwith an embedded reinforcing support in most cases (axial bellows;bellows with crossed layers);

[0003] a pressure reservoir comprising a first fastening area on whichthe one end of the pneumatic suspension bellows is secured by means of aclamping ring; as well as

[0004] a pneumatic suspension piston comprising a second fastening areaon which the other end of the pneumatic suspension bellows is secured bymeans of a clamping ring as well, as well as a roll-off piston on whoseouter wall the pneumatic suspension bellows is capable of rolling offwhile forming a first rolling fold.

[0005] A pneumatic suspension system of the type specified above isknown both in the manufacture of utility motor vehicles and passengercars (DE-A-198 19 642; DE-A-100 01 018).

[0006] Now, the problem of the invention is to further develop thepneumatic suspension system of the type specified above in such a mannerthat the comfort properties are enhanced.

[0007] Said problem is solved according to the characterizing part ofpatent claim 1 in that

[0008] the pressure reservoir is provided outside of the first fasteningarea with a contoured roll-off surface for a second roll-off fold thatincreases its outside diameter, and comprises a beginning and an end,said rolling fold constantly resting against the roll-off surface andbeing capable of rolling off only to a limited extent vis-à-vis thefirst rolling fold.

[0009] The two rolling folds, which are connected in series, lead to asubstantial improvement of the comfort properties.

[0010] Useful further developments of the pneumatic suspension system asdefined by the invention are specified in claims 2 to 9.

[0011] Now, the invention is explained in the following with the help ofan exemplified embodiment and by reference to a schematic drawing, towhich the following list of reference symbols is applicable:

[0012]1 Pneumatic suspension system

[0013]2 Pneumatic suspension bellows

[0014]3 Pressure reservoir (pneumatic suspension cover)

[0015]4 First fastening area

[0016]5 Clamping ring

[0017]6 Pneumatic suspension piston

[0018]7 Second fastening area

[0019]8 Clamping ring

[0020]9 Roll-off piston (immersing plunger)

[0021]10 First rolling fold

[0022]11 Contoured roll-off surface

[0023]12 Second rolling fold (pneumatic suspension loop)

[0024] D1 Outside diameter of first fastening area

[0025] D2 Outside diameter of second fastening area

[0026] D2 Outside diameter of roll-off piston

[0027] D4 Outside diameter of pressure reservoir

[0028] A Beginning of roll-off surface

[0029] B End of roll-off surface

[0030] X Axis of pneumatic suspension system

[0031] α Angle of roll-off surface

[0032] The important structural components of the pneumatic suspensionsystem 1 according to the only figure are the pneumatic suspensionbellows 2, the pressure reservoir 3 and the pneumatic suspension piston6. The pressure reservoir comprises in this connection a first fasteningarea 4 with an outside diameter D1, on which the one end of thepneumatic suspension bellows is secured by means of a clamping ring 5,whereby the outside diameter D1 includes the clamping ring. Thepneumatic suspension piston comprises a second fastening area 7 with anoutside diameter D2, on which the other end of the pneumatic suspensionbellows is secured by means of a clamping ring 8 as well, whereby theoutside diameter D2 includes the clamping ring also in the present case.Furthermore, the pneumatic suspension piston comprises a roll-off piston9 with an outside diameter D3, on whose outer wall the pneumaticsuspension bellows is capable of rolling off while forming a firstrolling fold 10.

[0033] Now, the pneumatic suspension system 1 as defined by theinvention is characterized in that the pressure reservoir 3 is providedoutside of the first fastening area 4, namely particularly in directconnection with said fastening area, with a contoured roll-off surface11 for a second rolling fold 12. Said contoured roll-off surfacecomprises a beginning A and an end B and increases the outside diameterD4. In this connection, the rolling fold always rests against theroll-off surface and can roll-off only to a limited extent as comparedto the first rolling fold 10.

[0034] Thus the outside diameter D4 of the pressure reservoir isincreased between the points A and B of the roll-off surface 11. Thediameter D4 is the largest at the end point B with respect to theroll-off surface. Beyond said end point B, the pressure reservoir 3mostly continues to extend substantially in a cylindrical form.

[0035] The roll-off surface 11 for the second rolling fold 12substantially extends in a conical form. Furthermore, the roll-offsurface and the first fastening area 4 of the pressure reservoir 3 mergeinto one another, forming one piece. Such a one-piece embodiment relatesin this connection to the direct fastening area 4 without including thepneumatic suspension bellows 2 and the clamping ring 5.

[0036] The roll-off surface 11 for the second rolling fold 12 extends atan angle α of from 15° to 70° based on the axis of the pneumaticsuspension system 1.

[0037] The following associations apply with respect to the outsidediameters D1, D2, D3 and D4:

[0038] D3>D1

[0039] D4>D2

[0040] D4>D3.

[0041] With respect to the outside diameter D4 of the pressure reservoir3, the end point B of the roll-off surface 11 applies as the referencepoint.

1. A pneumatic suspension system (1) at least comprising the followingstructural component of the pneumatic suspension: a pneumatic suspensionbellows (2), which is made of an elastomeric material encloses an airchamber with a variable volume and is provided with an embeddedreinforcement in most cases; a pressure reservoir (3) comprising a firstfastening area (4) with an outside diameter (D1), on which the one endof the pneumatic suspension bellows (2) is secured by means of aclamping ring (5), whereby the outside diameter. (D1) includes theclamping ring; as well as a pneumatic suspension piston (6) comprising asecond fastening area (7) with an outside diameter (D2), on which theother end of the pneumatic suspension bellows (2) is secured by means ofa clamping ring (8) as well, whereby the outside diameter (D2) includesthe clamping ring in the present, too, as well as a roll-off piston (9)with an outside diameter (D3) on whose outer wall the pneumaticsuspension bellows is capable of rolling off while forming a firstrolling fold (10); characterized in that the pressure reservoir (3) isprovided outside of the first fastening area (4) with a contouredroll-off surface (11) comprising a beginning (A) and an end (B) for asecond rolling fold (12) and increasing its outside diameter, saidsecond rolling fold constantly resting against the roll-off surface andbeing capable of rolling off only to a limited extent as compared to thefirst rolling fold (10).
 2. The pneumatic suspension system according toclaim 1, characterized in that the roll-off surface (11) for the secondrolling fold (12) extends in a substantially conical form.
 3. Thepneumatic suspension system according to claim 1 or 2, characterized inthat the roll-off surface (11) for the second rolling fold (12) directlyadjoins the first fastening area (4).
 4. The pneumatic suspension systemaccording to any one of claims 1 to 3, characterized in that theroll-off surface (11) for the second rolling fold (12) and the firstfastening area (4) of the pressure reservoir (3) merge into one another,forming one piece.
 5. The pneumatic suspension system according to anyone of claims 1 to 4, characterized in that the roll-off surface (11)for the second rolling fold (12) extends at an angle α of 15° to 70°based on the axis (X) of the pneumatic suspension system (1).
 6. Thepneumatic suspension system according to claim 5, characterized in thatthe roll-off surface (11) for the second rolling fold (12) extends at anangle α of 30° to 50°.
 7. The pneumatic suspension system according toany one of claims 1 to 6, characterized in that the followingassociation applies between the outside diameter (D1) of the firstfastening area (4) and the outside diameter (D3) of the roll-off piston(9): D3>D1.
 8. The pneumatic suspension system according to any one ofclaims 1 to 7, in particular in association with claim 7, characterizedin that the following association applies between the outside diameter(D2) of the second fastening area (7) and the increased outside diameter(D4) of the pressure reservoir (3) at the end point (B) of the roll-offsurface (11): D4>D2.
 9. The pneumatic suspension system according to anyone of claims 1 to 8, in particular in association with claims 7 and 8,characterized in that the following association applies between theoutside diameter (D3) of the roll-off piston (9) and the increasedoutside diameter (D4) of the pressure reservoir (3) at the end point (B)of the roll-surface (11): D4>D3.